Full scale frost heave tests

The frost susceptibility of soils is usually determined after laboratory freezing tests. The results are to a great extent dependent on the design of these tests. One major drawback of this form of test consists in the difficulty of interpreting the results in terms of field behaviour. In order to discover the frost behaviour of soils in the field, a full scale test was initiated by the Swedish National Road Administration. Its purpose was to develop a method whereby most of the known heave parameters could be controlled, and to evaluate the relevance of the method chosen to the classification of the frost susceptibility of soils. The test was performed as a laboratory freezing experiment. Four cylinders were constructed of concrete rings. The cylinders were filled with layers of soils with different susceptibility to frost. The water level was kept constant. The test continued through four winters, during which soil temperature, frost depth, frost heave, frost index and accumulated water were recorded. The results showed that the method chosen can be used for classification of frost susceptibility. Difficulties arose, however, in the interpretation of the results, mainly because of the layering of different soils. Future tests should be carried out with one soil in each cylinder. It was not possible to determine the influence of permeability on frost heave. The decline of the thermal gradient seems to be more important for frost heave rate than the increase in load pressure, although the load pressure affects the amount of heave, which is relevant to the frost heave on roads. /TRRL/